1
Q
What are the environmental factors that significantly impact microorganisms?
A
- Nutrient and energy sources
- Temperature
- Gas content
- Water
- Salt
- pH
- Radiation
- Other organisms
These factors affect the survival of microorganisms in their habitats.
2
Q
The process through which microorganisms adjust their anatomy and physiology to survive is called _______.
A
adaptation
Adaptability allows microbes to inhabit all parts of the biosphere and is a major force behind species evolution.
3
Q
What are essential nutrients?
A
Any substance that an organism must get from a source outside its cells
Essential nutrients are processed and transformed into the chemicals of the cell.
4
Q
Name the two categories of essential nutrients.
A
- Macronutrients
- Micronutrients
Macronutrients are required in large quantities, while micronutrients are present in smaller amounts.
5
Q
Examples of macronutrients include:
A
- Sugars
- Amino acids
Macronutrients play principal roles in cell structure and metabolism.
6
Q
Examples of micronutrients or trace elements include:
A
- Manganese
- Zinc
- Nickel
Micronutrients are involved in enzyme function and maintenance of protein structure.
7
Q
What is the difference between organic and inorganic nutrients?
A
Organic nutrients contain carbon and hydrogen; inorganic nutrients lack some combination of both
Organic nutrients are typically products of living things.
8
Q
What is the highest component in the water content of Escherichia coli?
A
70%
Water content is the highest of all components in the cell.
9
Q
What percentage of the dry cell weight of Escherichia coli is composed of organic compounds?
A
97%
This indicates the predominance of organic compounds in the cell.
10
Q
Which six elements, represented by CHONPS, compose about 96% of the cell?
A
- Carbon
- Hydrogen
- Oxygen
- Nitrogen
- Phosphorus
- Sulfur
These elements are essential for cell growth.
11
Q
True or false: A cell as simple as E. coli contains on the order of 5,000 different compounds.
A
TRUE
Despite its simplicity, E. coli synthesizes a great diversity of compounds from a few types of nutrients.
12
Q
What are some examples of nutrients that E. coli needs to absorb?
A
- (NH4)2SO4
- FeCl2
- NaCl
- Trace elements
- Glucose
- KH2PO4
- MgSO4
- CaHPO4
- Water
These nutrients are essential for the growth and function of E. coli.
13
Q
The cycle of elements from an inorganic form in an environmental reservoir to an organic form in organisms is known as _______.
A
nutrient cycling
This process is crucial for the overall cycle of life on the planet.
14
Q
What is the main source of energy for most organisms on earth?
A
Sunlight
Photosynthesizers use sunlight to produce organic nutrients that feed other organisms.
15
Q
How do nonphotosynthetic organisms power their cells?
A
By extracting energy from chemical reactions
They do not rely on sunlight for energy.
16
Q
What gases are essential to living processes and found in the atmosphere?
A
- Nitrogen
- Oxygen
- Carbon dioxide
These gases serve as a reservoir for living organisms.
17
Q
Where do many inorganic nutrients originate from?
A
- Air
- Water
- Bedrock
These nutrients are released into the environment through decomposition and synthesis.
18
Q
What type of communities do microbes form in various habitats?
A
Complex communities
Microbes must associate physically and share habitats, often establishing biofilms.
19
Q
Microorganisms can be found living along a wide temperature scale. True or False?
A
TRUE
The temperature of habitats ranges significantly throughout the biosphere.
20
Q
What is the pH range of habitats where microbes can adapt?
A
From acidic (pH 0) to alkaline (pH 12)
Microbes have adapted to various pH levels.
21
Q
What defines the two basic nutritional groups based on carbon source?
A
- Heterotrophs
- Autotrophs
The source of carbon is key to the structure and metabolism of all life forms.
22
Q
Define a heterotroph.
A
An organism that must obtain its carbon in an organic form
Heterotrophs are nutritionally dependent on other life forms.
23
Q
What are some common organic molecules that heterotrophs can use?
A
- Proteins
- Carbohydrates
- Lipids
- Nucleic acids
These nutrients provide essential carbon for heterotrophs.
24
Q
What is an autotroph?
A
An organism that uses inorganic CO2 as its carbon source
Autotrophs convert CO2 into organic compounds and are not nutritionally dependent on other living things.
25
True or false: All **heterotrophs** can use the same organic carbon sources.
FALSE
## Footnote
Some heterotrophs are restricted to a few substrates, while others can metabolize hundreds of different substrates.
26
What are examples of **organic nutrients** that can be absorbed without digestion?
* Monosaccharides
* Amino acids
## Footnote
These nutrients exist in a form simple enough for absorption.
27
What must many larger molecules do before absorption in heterotrophs?
Be digested by the cell
## Footnote
Not all organic nutrients are in a form that can be directly absorbed.
28
Fill in the blank: An **autotroph** is an organism that uses inorganic CO2 as its _______.
carbon source
## Footnote
This characteristic allows autotrophs to convert CO2 into organic compounds.
29
What is the primary distinction between **carbon source** and **carbon function** in cells?
Carbon source refers to the form of carbon compounds absorbed as nutrients, while carbon function pertains to the role of carbon compounds in cell structure and metabolism
## Footnote
Most carbon compounds involved in cell metabolism are organic, even if the source is inorganic like carbon dioxide.
30
Define **growth factors** in the context of microbial nutrition.
Essential nutrients that cannot be synthesized by an organism and must be provided as a nutrient
## Footnote
Examples include amino acids, nitrogenous bases, and vitamins.
31
What are **essential amino acids**?
Amino acids that must be obtained from food because the organism cannot synthesize them
## Footnote
All cells require 20 different amino acids for proper protein assembly.
32
Which bacterium requires specific growth factors such as hemin and NAD+ for growth?
Haemophilus influenzae
## Footnote
This bacterium causes meningitis and respiratory infections in humans.
33
List the **main categories of nutritional types** among organisms.
* Autotrophs
* Heterotrophs
## Footnote
These categories are based on the sources of carbon and energy.
34
Differentiate between **autotrophs** and **heterotrophs**.
Autotrophs use CO2 as a carbon source; heterotrophs use organic carbon
## Footnote
Autotrophs can be further classified into photoautotrophs and chemoautotrophs.
35
What are the two types of **autotrophs** based on their energy sources?
* Photoautotrophs
* Chemoautotrophs
## Footnote
Photoautotrophs derive energy from sunlight, while chemoautotrophs derive energy from chemical reactions involving simple chemicals.
36
What is the process of **photosynthesis** in photoautotrophs?
The capture of light energy to convert CO2 into simple organic compounds
## Footnote
This process relies on special pigments and can be oxygenic or anoxygenic.
37
What is the equation for **oxygenic photosynthesis**?
6 CO2 + 6 H2O + light energy → C6H12O6 + 6 O2
## Footnote
This type of photosynthesis occurs in plants, algae, and cyanobacteria.
38
What are **phototrophs**?
Microbes that acquire energy from light
## Footnote
They include organisms that perform photosynthesis.
39
What are **chemotrophs**?
Microbes that gain energy from chemical compounds
## Footnote
They include certain bacteria and archaea.
40
Fill in the blank: **Microbes that metabolize organic matter from dead organisms are called __________.**
Saprobes
## Footnote
Saprobes play a crucial role in decomposition.
41
Fill in the blank: **Microbes that obtain organic matter from living organisms are called __________.**
Symbiotic microbes
## Footnote
This category includes parasites, commensals, and mutualistic microbes.
42
What are the primary producers in most ecosystems that constitute the basis of food chains?
Organisms that perform photosynthesis
## Footnote
They provide nutrition for heterotrophs and maintain oxygen levels in the atmosphere.
43
What is the other form of **photosynthesis** that does not produce oxygen?
Anoxygenic photosynthesis
## Footnote
It uses hydrogen sulfide gas and produces elemental sulfur.
44
List the four key differences of **anoxygenic photosynthesis**.
* Uses bacteriochlorophyll
* Hydrogen source is hydrogen sulfide gas
* Produces elemental sulfur
* Occurs in the absence of oxygen
## Footnote
Common groups include purple and green sulfur bacteria.
45
What are **chemoautotrophs**?
Bacteria or archaea that survive on inorganic substances
## Footnote
They require neither light nor organic nutrients.
46
How do **chemoautotrophs** derive energy?
By removing electrons from inorganic substrates
## Footnote
They combine them with other inorganic substances to release simple organic molecules.
47
What is the unique type of **chemoautotroph** that produces methane gas?
Methanogens
## Footnote
All known methanogens are archaea found in extreme habitats.
48
Where can **methanogens** be commonly found?
* Hot springs
* Vents
* Deep ocean
* Soil
* Swamps
* Intestines of humans and animals
## Footnote
They play a role in producing methane gas under anaerobic conditions.
49
What is the metabolic process of **methanogens** summarized by?
4 H₂ + CO₂ → CH₄ + 2 H₂O
## Footnote
This process occurs under anaerobic conditions.
50
True or false: **Chemoautotrophs** require light to survive.
FALSE
## Footnote
They survive entirely on inorganic substances without the need for light.
51
What significant role do **chemoautotrophs** play in ecosystems?
Recycling inorganic nutrients and elements
## Footnote
They are crucial for nutrient cycling in various environments.
52
What is the estimated proportion of life on the planet that **methanogens** comprise?
Nearly one-third
## Footnote
This estimate is based on their massive deposits found deep beneath the seafloor.
53
What is the primary niche of **saprobes**?
* Decomposers of plant litter
* Decomposers of animal matter
* Decomposers of dead microbes
## Footnote
Saprobes recycle nutrients and prevent the accumulation of organic material.
54
True or false: **Saprobes** can engulf large particles of food.
FALSE
## Footnote
Saprobes release enzymes to digest food particles into smaller molecules for transport into the cell.
55
What are the two categories of **parasitic microorganisms** based on their location?
* Ectoparasites
* Endoparasites
## Footnote
Ectoparasites live on the body, while endoparasites live in organs and tissues.
56
What is the definition of a **parasite**?
A microbe that invades a host, uses it as a habitat and nutrient source, and harms the host
## Footnote
Parasitic microbes that cause damage are also termed pathogens.
57
What is the principal energy-yielding pathway in animals, protozoa, fungi, and aerobic bacteria?
Aerobic respiration
## Footnote
This process is an example of **chemoheterotrophy**.
58
Fill in the blank: **Chemoheterotrophic microbes** require an organic _______.
carbon source
## Footnote
They differ in how they obtain this organic carbon.
59
What are the two main processes through which **chemoorgano-trophs** release energy?
* Respiration
* Fermentation
## Footnote
These processes release energy in the form of ATP.
60
What is the relationship between **photosynthesis** and aerobic respiration?
Complementary
## Footnote
The products of one process serve as the reactants for the other.
61
What is an example of a **facultative parasite**?
Pseudomonas aeruginosa
## Footnote
It is primarily found in soil and water but can infect compromised hosts.
62
What are the two synonyms for **saprobes**?
* Saprotrh
* Saprophyte
## Footnote
The terms saprobe and saprotraph are preferred for consistency.
63
What is the significance of **methane** in relation to climate change?
It is an important greenhouse gas
## Footnote
Rises in sea temperature could increase the melting of methane deposits, contributing to climate change.
64
What is the role of the **cell wall** in microorganisms?
Acts as a barrier
## Footnote
The cell wall is inflexible and cannot engulf large pieces of organic debris.
65
What happens to **enzymes** in the process of extracellular digestion?
* Transported outside the wall
* Hydrolyze bonds on nutrients
## Footnote
Enzymes are synthesized in response to usable food substrates.
66
What is the process by which smaller molecules are transported into the cytoplasm?
Transport across the wall and cell membrane
## Footnote
This occurs after digestion produces small enough molecules.
67
Define **obligate parasites**.
Parasites that cannot grow outside of their host
## Footnote
Examples include the leprosy bacillus and the syphilis spirochete.
68
What distinguishes **chemoautotrophs** from **chemoheterotrophs**?
* Chemoautotrophs: use inorganic compounds for carbon and energy
* Chemoheterotrophs: require organic compounds for carbon and energy
## Footnote
They have different nutritional strategies.
69
What are the main differences between **saprobes**, **symbionts**, and **parasites**?
* Saprobes: feed on dead organic matter
* Symbionts: live in close association with another organism, often benefiting both
* Parasites: live on or in a host, often harming it
## Footnote
Each has a unique relationship with their nutrient sources.
70
Describe the basic factors in **diffusion**.
* Movement of molecules from high to low concentration
* Random thermal motion
## Footnote
Diffusion results in the even distribution of molecules in a solution.
71
Define **osmosis**.
The diffusion of water across a selectively permeable membrane
## Footnote
Osmosis is influenced by varying osmotic conditions.
72
What adaptations do microbes make in response to **osmosis**?
Adaptations to maintain internal balance of solutes and water
## Footnote
These adaptations help microbes survive in different osmotic environments.
73
Describe the features of **active transport**.
* Requires energy
* Moves substances against their concentration gradient
## Footnote
Active transport mechanisms include pumps and vesicular transport.
74
True or false: The **cell membrane** is specialized for the transport of substances across it.
TRUE
## Footnote
Transport occurs across the cell membrane even in organisms with cell walls.
75
What is the process called when water diffuses through a **selectively permeable membrane**?
osmosis
## Footnote
Osmosis is a physical phenomenon demonstrated in laboratory experiments with nonliving materials.
76
In osmosis, water moves from an area of _______ concentration to an area of lower concentration.
higher
## Footnote
This movement continues until equilibrium is reached.
77
What are the three terms used to describe osmotic conditions affecting cells?
* isotonic
* hypotonic
* hypertonic
## Footnote
These terms refer to the solute concentration of the environment outside the cell.
78
Under **isotonic** conditions, what happens to the cell's volume?
No net change
## Footnote
Isotonic solutions are stable environments for cells.
79
What occurs to a cell in a **hypotonic** environment?
Cells swell and can burst
## Footnote
Pure water is the most hypotonic environment for cells.
80
What is the term for the condition when a cell's protoplast shrinks away from the cell wall due to water loss in a **hypertonic** environment?
plasmolysis
## Footnote
This condition can damage or kill many types of cells.
81
True or false: **Hypertonic** solutions can inhibit the growth of microbial contaminants.
TRUE
## Footnote
Concentrated salt and sugar solutions are used as preservatives for food.
82
What is the driving force behind **diffusion** in cell activities?
Concentration gradient
## Footnote
Diffusion is a passive transport process that does not require energy.
83
What happens to the rate of osmosis when the concentrations of solutions differ?
One side experiences a net loss of water, the other a net gain
## Footnote
This continues until equilibrium is reached.
84
What is the effect of **hypotonicity** on bacteria with rigid cell walls?
Slight hypotonicity is tolerated well
## Footnote
The flow of water keeps the cell membrane fully extended.
85
What is the **osmotic process** demonstrated in the model system?
Water diffuses from higher concentration (outer container) to lower concentration (sac)
## Footnote
The net gradient favors osmosis into the sac, and equilibrium will not occur.
86
What happens to the volume in the sac as **H2O** diffuses into it?
Volume increases, forcing excess solution into the tube
## Footnote
This process continues as long as there is a concentration gradient.
87
True or false: In hypotonic conditions, cells like algae have a cell wall that protects them from bursting.
TRUE
## Footnote
Algae have a cell wall that prevents bursting even as the cytoplasmic membrane becomes turgid.
88
How does an **amoeba** adapt to hypotonic conditions?
Uses a contractile vacuole to siphon excess water out
## Footnote
The amoeba lacks a cell wall, necessitating energy expenditure to manage water influx.
89
What physiological adaptation do **halobacteria** have in high-salt environments?
Absorb salt to make cells isotonic with the environment
## Footnote
They thrive in habitats with high-salt concentrations, such as the Great Salt Lake.
90
What is **facilitated diffusion**?
A passive transport mechanism using carrier proteins to move substances across membranes
## Footnote
Carrier proteins exhibit specificity and saturation in their transport capabilities.
91
What do carrier proteins in facilitated diffusion do when they bind a specific substance?
Change conformation to facilitate movement across the membrane
## Footnote
After transport, the carrier protein returns to its original shape.
92
What is the **specificity** of carrier proteins in facilitated diffusion?
They bind and transport only a single type of molecule
## Footnote
For example, a sodium transporter will not bind glucose.
93
What limits the rate of transport in facilitated diffusion?
The number of binding sites on the transport proteins
## Footnote
As concentration increases, transport rate increases until all binding sites are occupied.
94
What are **aquaporins**?
Passive protein carriers that facilitate transport of water
## Footnote
They are also known as water channels found in a variety of cells.
95
What is an **Isotonic Solution**?
Water concentration is equal inside and outside the cell, thus rates of diffusion are equal in both directions.
## Footnote
This condition maintains cell shape and function.
96
What happens to a cell in a **Hypotonic Solution**?
Net diffusion of water is into the cell; this swells the protoplast and pushes it tightly against the wall. Wall usually prevents cell from bursting.
## Footnote
This process can lead to cell turgor.
97
What is the process called when a cell shrinks away from its cell wall in a **Hypertonic Solution**?
Plasmolysis
## Footnote
This occurs when water diffuses out of the cell.
98
What is the term for the movement of substances across the cell membrane?
Transport
## Footnote
This includes both passive and active mechanisms.
99
What is **Facilitated Diffusion**?
Involves the attachment of a molecule to a specific protein carrier, causing a conformational change in the protein that facilitates the molecule's passage across the membrane.
## Footnote
The cell does not have to expend energy for transport.
100
What is the role of **Active Transport** in cells?
Bringing in molecules against a gradient
## Footnote
This is crucial for cells in nutrient-starved conditions.
101
What occurs during **Osmolysis**?
Water diffuses into the cell causing it to swell, and may burst if no mechanism exists to remove the water.
## Footnote
This is a critical process in maintaining cell integrity.
102
What happens to a cell when water diffuses out of it?
The cell shrinks and becomes distorted.
## Footnote
This can affect the cell's functionality.
103
What is the function of molecules that follow an existing **osmotic gradient**?
They appear to be involved in regulating volume and osmotic pressure.
## Footnote
This is essential for maintaining homeostasis within the cell.
104
What is the **Cell Membrane**'s role?
It regulates the movement of substances in and out of the cell.
## Footnote
This is vital for maintaining cellular homeostasis.
105
What is the role of **solute-binding proteins** in carrier-mediated active transport?
They interact with nearby transporter proteins to carry essential solutes
## Footnote
Essential solutes include sodium, iron, and sugars.
106
In carrier-mediated active transport, what is generated to pump the solute into the cell's interior?
Energy from activated ATP
## Footnote
This process involves membrane-bound transporter proteins (permeases).
107
What is **group translocation**?
A process where a specific molecule is actively captured and chemically altered during transport
## Footnote
This mechanism conserves energy by coupling transport with synthesis.
108
What are the two types of **endocytosis** mentioned?
* Phagocytosis
* Pinocytosis
## Footnote
Phagocytosis involves solid particles, while pinocytosis involves fluids and dissolved substances.
109
What is the function of **microvilli** in pinocytosis?
They enclose fluids and/or dissolved substances in vesicles
## Footnote
Microvilli are fine protrusions that facilitate this process.
110
List the **features inherent in active transport systems**.
* Transport of nutrients against the diffusion gradient
* Presence of specific membrane proteins (permeases and pumps)
* Expenditure of cellular energy in the form of ATP
## Footnote
Active transport allows for nutrient concentrations to be higher inside the cell than in the environment.
111
What types of substances are transported actively in cells?
* Monosaccharides
* Amino acids
* Organic acids
* Phosphates
* Metal ions
## Footnote
These substances can be found in intracellular concentrations much higher than in the habitat.
112
What is the **nature of transport** that does not require energy expenditure by the cell?
Passive transport
## Footnote
Substances move from areas of higher concentration toward areas of lower concentration.
113
Name the **examples** of passive transport.
* Diffusion
* Osmosis
* Facilitated diffusion
## Footnote
These processes allow substances to move across membranes without energy input.
114
What type of transport requires **energy expenditure** by the cell?
Active transport
## Footnote
Molecules may not exist in a gradient and transport can occur against a concentration gradient.
115
What are the **types** of active transport?
* Carrier-mediated active transport
* Group translocation
* Bulk transport
## Footnote
Each type has specific mechanisms for moving substances across membranes.
116
Describe **carrier-mediated active transport**.
Involves specific membrane proteins that bind ATP and molecules to be transported
## Footnote
Energy from ATP drives the movement through the protein carrier.
117
What is **group translocation**?
Transport of a nutrient coupled with its conversion to a metabolically useful substance
## Footnote
Used by certain bacteria to transport sugars while adding phosphate molecules.
118
What is **endocytosis**?
Transport of large molecules, particles, or liquids across cell membranes
## Footnote
Involves enclosing substances in the membrane to form a vacuole.
119
What is **phagocytosis**?
A type of endocytosis where cells ingest whole cells or large solid matter
## Footnote
Commonly performed by amoebas and certain white blood cells.
120
What is **pinocytosis**?
A type of endocytosis for liquids or molecules in solution
## Footnote
Allows cells to take in fluids and dissolved substances.
121
What is **Brownian movement**?
A fundamental property of atoms and molecules in random motion
## Footnote
It describes the movement of small uncharged molecules across membranes.
122
What drives the **pumping** of atoms or molecules into or out of the cell?
ATP or other high-energy molecules
## Footnote
This process is essential for active transport mechanisms.
123
Differentiate between **habitat** and **niche**.
Habitat: the environment where an organism lives; Niche: the role or function of an organism within its habitat
## Footnote
Understanding these concepts is crucial for studying microbial ecology.
124
What are the **adaptive temperature groups** of microbes?
* Psychrophiles
* Mesophiles
* Thermophiles
* Hyperthermophiles
## Footnote
Each group has specific temperature ranges for optimal growth.
125
List the **major gases** required by microbes.
* Oxygen
* Carbon dioxide
* Nitrogen
* Hydrogen
## Footnote
Microbial requirements for these gases vary significantly among different species.
126
How do microbes adapt to **variations in pH**?
By altering their metabolic processes and enzyme activity
## Footnote
Different microbial groups have specific adaptations to thrive in varying pH environments.
127
Identify microbial adaptations to **osmotic pressure**.
* Production of osmoprotectants
* Alteration of cell wall structure
* Regulation of internal solute concentrations
## Footnote
These adaptations help microbes survive in environments with varying osmotic conditions.
128
What does **microbial ecology** focus on?
Ways microorganisms deal with or adapt to environmental factors
## Footnote
Environmental factors include heat, cold, gases, acid, radiation, osmotic and hydrostatic pressures, and other microbes.
129
The term used by biologists to describe the totality of adaptations organisms make to their habitats is **________**.
niche
## Footnote
Niche refers to the specific role or function of an organism within its environment.
130
What fundamentally affects the function of **metabolic enzymes** in microbes?
Environmental factors
## Footnote
Survival depends on whether enzyme systems can function in changing environments.
131
Microbial cells cannot control their **temperature** and must adapt to their **________**.
ambient temperature
## Footnote
This adaptation is crucial for survival in varying temperature conditions.
132
What are the **three cardinal temperatures** for microbial growth?
* Minimum temperature
* Maximum temperature
* Optimum temperature
## Footnote
These temperatures define the range for growth and metabolism.
133
The **minimum temperature** is defined as what?
The lowest temperature that permits a microbe's continued growth and metabolism
## Footnote
Below this temperature, microbial activities are inhibited.
134
What happens if the temperature rises slightly above the **maximum temperature**?
Growth will stop
## Footnote
Continued rise beyond maximum can lead to enzyme and nucleic acid inactivation, known as denaturation.
135
The **optimum temperature** promotes what?
The fastest rate of growth and metabolism
## Footnote
It is usually a small range between the minimum and maximum temperatures.
136
Some strict parasites will not grow if the temperature varies more than a few degrees from the host's **________**.
body temperature
## Footnote
For example, rhinoviruses multiply successfully only at slightly below normal body temperature.
137
Strains of **Staphylococcus aureus** grow within what temperature range?
6°C to 46°C (43°F to 114°F)
## Footnote
This demonstrates the broad adaptability of some microbes to temperature variations.
138
The intestinal bacterium **Enterococcus faecalis** grows within what temperature range?
0°C to 44°C (32°F to 112°F)
## Footnote
This indicates its ability to thrive in cooler environments.
139
Another way to express temperature adaptation is to describe whether an organism grows optimally in **________**, moderate, or hot conditions.
cold
## Footnote
This classification helps in understanding microbial growth preferences.
140
What is a **psychrophile**?
A microorganism with an optimum temperature below 15°C (59°F) and can grow at 0°C (32°F)
## Footnote
Psychrophiles are obligate cold organisms and cannot grow above 20°C (68°F).
141
What temperature range can **psychrophiles** grow at?
0°C to 15°C
## Footnote
They generally cannot grow above 20°C (68°F).
142
True or false: **Psychrophiles** can survive in the human body.
FALSE
## Footnote
Psychrophiles do not cause infections and are not capable of surviving in the human body.
143
Where can **psychrophiles** be found?
* Snowfields
* Polar ice
* Permafrost
* Deep ocean
## Footnote
They populate some of the coldest places on earth.
144
What is the challenge of working with **true psychrophiles** in the laboratory?
Inoculations must be done in a cold room
## Footnote
Ordinary room temperature can be lethal to these organisms.
145
What is the optimum growth temperature for **psychrophiles**?
Below 15°C
## Footnote
They can grow at or near 0°C.
146
What is a **psychrotroph**?
A type of mesophile capable of growth below 20°C
## Footnote
Mesophiles generally grow between 10°C and 50°C.
147
What is the temperature requirement for **thermophiles**?
Above 45°C
## Footnote
They grow optimally between 45°C and 80°C.
148
What are **extreme thermophiles** also known as?
Hyperthermophiles
## Footnote
They have optimal growth temperatures above 80°C.
149
What is the general growth temperature range for **mesophiles**?
10°C to 50°C
## Footnote
Their optimal growth usually falls between 20°C and 40°C.
150
What type of organisms are classified as **psychrophilic photosynthetic organisms**?
* Chlamydomonas nivalis
## Footnote
These organisms thrive in cold environments, such as the surface of Alaskan glaciers.
151
What is the temperature range for **mesophiles**?
* 10°C to 50°C (50°F to 122°F)
## Footnote
Most human pathogens have optima between 30°C and 40°C.
152
What are **thermoduric microbes** known for?
* Surviving short exposure to high temperatures
* Common contaminants of heated or pasteurized foods
## Footnote
Examples include Giardia and sporeformers like Bacillus and Clostridium.
153
Define **thermophile**.
A microbe that grows optimally at temperatures greater than 45°C (113°F)
## Footnote
Thermophiles are found in environments like volcanic soil and compost piles.
154
What is the temperature range for **thermophiles**?
* 45°C to 80°C (113°F to 176°F)
## Footnote
Most eukaryotic forms cannot survive above 60°C.
155
What are **hyperthermophiles** adapted to?
* Life in extreme temperatures
* Growing at temperatures between 80°C and 121°C (250°F)
## Footnote
They endure the highest temperature limits for enzymes and cell structures.
156
What is **Taq polymerase** and why is it significant?
An enzyme produced by Thermus aquaticus that can make copies of DNA at high temperatures
## Footnote
It is essential for the polymerase chain reaction (PCR) used in medicine and biotechnology.
157
What are the two atmospheric gases that most influence microbial growth?
* Oxygen (O2)
* Carbon dioxide (CO2)
## Footnote
Oxygen is crucial for respiration and can exist in toxic forms.
158
What is an **aerobe**?
An organism that can use gaseous oxygen in its metabolism
## Footnote
Obligate aerobes cannot grow without oxygen.
159
What is the difference between an **obligate aerobe** and a **facultative anaerobe**?
* Obligate aerobe: Cannot grow without oxygen
* Facultative anaerobe: Can grow with or without oxygen
## Footnote
Facultative anaerobes metabolize by aerobic respiration when oxygen is present and switch to fermentation in its absence.
160
What are the toxic products that can be formed from oxygen in microbial processes?
* Singlet oxygen (O2)
* Superoxide ion (O2)
* Hydrogen peroxide (H2O2)
* Hydroxyl radicals (OH)
## Footnote
These products can damage and destroy cells.
161
What enzymes are involved in the detoxification of superoxide ion?
* Superoxide dismutase
* Catalase
* Peroxidase
## Footnote
These enzymes help convert superoxide into less harmful substances.
162
What is a **microaerophile**?
An organism that requires a small amount of oxygen (19-15%) for metabolism but does not grow at normal atmospheric concentrations
## Footnote
Most microaerophiles live in habitats like soil, water, or the human body that provide limited oxygen.
163
What is a **true anaerobe**?
An organism that lacks the metabolic enzyme systems for using oxygen gas in respiration and cannot tolerate free oxygen
## Footnote
Strict anaerobes live in highly reduced habitats such as deep muds, lakes, oceans, and soil.
164
What is the role of **thioglycollate** in determining oxygen requirements of microbes?
It is a reducing medium that contains an oxygen-removing chemical, helping to establish a gradation in oxygen content
## Footnote
The location of growth in a tube of thioglycollate medium indicates an organism's adaptation to oxygen use.
165
What are common sites for **anaerobic infections**?
* Dental caries
* Large intestine
* Following abdominal surgery
* Traumatic injuries (e.g., gas gangrene, tetanus)
## Footnote
These sites can harbor strictly anaerobic bacteria.
166
What are **aerotolerant anaerobes**?
Organisms that do not utilize oxygen gas but can survive and grow in its presence without being harmed
## Footnote
Some possess alternate mechanisms for breaking down peroxide and superoxide.
167
What are **capnophiles**?
Microbes that grow best at higher CO2 concentrations (3%-10%) than are normally present in the atmosphere
## Footnote
This is important for isolating certain pathogens from clinical specimens.
168
True or false: **Strict anaerobes** can tolerate free oxygen in their environment.
FALSE
## Footnote
Strict anaerobes will die if exposed to free oxygen.
169
What is the significance of **growing strictly anaerobic bacteria**?
Requires special media, methods of incubation, and handling chambers that exclude oxygen
## Footnote
This ensures that the anaerobes are not exposed to harmful oxygen.
170
What is the role of **CO₂** for autotrophs?
Essential nutrient for synthesizing organic compounds
## Footnote
Autotrophs utilize CO₂ in their metabolic processes.
171
The **pH scale** ranges from ____ to ____.
0 to 14
## Footnote
pH 7 is neutral, below 7 is acidic, and above 7 is alkaline.
172
Most microorganisms thrive in habitats with a pH between ____ and ____.
pH 6 and pH 8
## Footnote
Extreme pH levels can damage enzymes and cellular substances.
173
What are **obligate acidophiles**? Give an example.
* Euglena mutabilis
* Thermoplasma
## Footnote
These organisms thrive in highly acidic environments.
174
What do **alkalinophiles** require for growth?
High levels of basic minerals
## Footnote
They can tolerate environments with high pH, such as Mono Lake.
175
What is the optimal NaCl concentration for **obligate halophiles**?
25% NaCl
## Footnote
They require at least 9% NaCl for growth.
176
True or false: **Osmophiles** live in habitats with low solute concentration.
FALSE
## Footnote
Osmophiles thrive in high solute concentrations.
177
What do **osmotolerant** organisms do?
Adapt to wide concentrations in solutes
## Footnote
They can survive in varying salt concentrations.
178
What is the significance of **barophiles**?
They exist under high hydrostatic pressure
## Footnote
Found in deep-sea environments, they can rupture at normal pressures.
179
Why do all cells require **water**?
For growth and metabolism
## Footnote
Water is essential for enzyme function and nutrient diffusion.
180
What are **psychrophiles** and **thermophiles** known for?
Surviving in cold and hot environments, respectively
## Footnote
They play ecological roles in extreme temperature habitats.
181
What is an **obligate intracellular parasite**? Name three groups.
* Viruses
* Chlamydia
* Rickettsia
## Footnote
They require a host cell for replication.
182
Where in the body are **anaerobic habitats** commonly found?
In the intestines and deep tissues
## Footnote
Anaerobic conditions are prevalent in these areas.
183
What are the toxic effects of **superoxide ions** and **hydrogen peroxide**?
Damage cellular components
## Footnote
They are byproducts of aerobic metabolism and can be harmful.
184
Differentiate between **mutual, commensal, and parasitic associations**.
* Mutual: both benefit
* Commensal: one benefits, other unaffected
* Parasitic: one benefits at the other's expense
## Footnote
These associations describe different interactions among microorganisms.
185
What is **syntrophy**?
Cooperation between two organisms to degrade a substance
## Footnote
An example is the breakdown of organic matter by different microbes.
186
What is **amensalism**?
One organism is harmed while the other is unaffected
## Footnote
An example is the inhibition of one species by the metabolic products of another.
187
Describe the interactions between **humans and their microbiota**.
Mutualistic relationships that aid digestion and immunity
## Footnote
Microbiota play essential roles in human health.
188
What are the **six basic patterns** of microbial alliances?
1. Codependent existence
2. Free-living microbes
3. Loose interactions
4. Temporary unions
5. Symbiosis
6. Other associations
## Footnote
These patterns range from completely interdependent relationships to more casual interactions.
189
Define **symbiosis**.
Close associations between organisms advantageous to at least one member
## Footnote
Symbiosis includes various forms, such as mutualism and parasitism.
190
True or false: **Symbiosis** refers only to mutually beneficial associations.
FALSE
## Footnote
Symbiosis also includes parasitism, which is not mutually beneficial.
191
What are the two types of **symbionts** based on their living arrangement?
* Endosymbionts
* Ectosymbionts
## Footnote
Endosymbionts live internally, while ectosymbionts are attached to the outside surfaces of their partners.
192
What is the most intimate type of **symbiosis**?
Mutualism
## Footnote
In mutualism, all members share the benefits of the relationship.
193
Define **coevolution**.
Process where coevolving symbionts adapt together over time
## Footnote
Changes in one partner exert selective pressure on the other, leading to mutual adaptations.
194
What is **obligate mutualism**?
Organisms require each other to survive
## Footnote
Examples include root nodules with nitrogen-fixing bacteria and jellyfish with dinoflagellates.
195
What do **root nodules** contain that benefits the plant?
Nitrogen-fixing endosymbiotic bacteria
## Footnote
These bacteria supply the plant with usable nitrogen.
196
What is the role of **dinoflagellates** in jellyfish and corals?
Provide color and nutrition
## Footnote
Jellyfish like Casseopeia rely on these endosymbiotic algae for survival.
197
What is **nonobligate mutualism**?
Organisms interact for mutual benefit but can live apart
## Footnote
Example: Protozoan engulfs algae and absorbs nutrients while sheltering them.
198
In nonobligate mutualism, what does the **plant** supply to the **fungus**?
Nutrients
## Footnote
The fungus protects the plant against drying and insects.
199
What is **commensalism**?
One partner is favored, the other is not harmed or helped
## Footnote
Example: Haemophilus absorbs growth factors from Staphylococcus.
200
What do **human commensals** associated with the epidermis feed on?
Flakes and excretions
## Footnote
Generally, they have neutral effects on humans.
201
What is **parasitism**?
A microbe invades a host and causes damage
## Footnote
All viruses are parasites that invade cells.
202
What type of parasite is the **malaria vector**?
Ectoparasite
## Footnote
The female Anopheles mosquito is a blood-sucking ectoparasite of humans.
203
What does the **Sin Nombre hantavirus** represent?
A human pathogen carried in the waste of mice
## Footnote
It exemplifies parasitism as it invades host tissues.
204
What is **syntrophy** in microbial interactions?
Microbes sharing a habitat feed off substances released by other organisms
## Footnote
Example: Azotobacter releases NH4 that feeds Cellulomonas, and Cellulomonas degrades cellulose that feeds Azotobacter.
205
Define **amensalism**.
One member of an association produces a substance that harms or kills another
## Footnote
Example: Ants cultivate actinomycetes to protect their habitat from microbial pests.
206
What is the role of **actinomycetes** in ant ecology?
Produce antibiotics to inhibit undesirable fungi
## Footnote
Example: Antibiosis by an actinomycete against a pathogenic fungus.
207
What is **obligate mutualism**?
A relationship where both partners are completely interdependent
## Footnote
Example: Buchnera endosymbionts of certain aphids provide amino acids and require a protective habitat.
208
What is the significance of **endosymbiotic bacteria**?
They likely gave rise to mitochondria and chloroplasts of eukaryotic cells
## Footnote
Example: Obligate mutualism in termites, corals, and root nodules.
209
What is **cooperation** in mutualistic relationships?
Nondependent forms of mutualism where organisms gain mutual benefit but can survive independently
## Footnote
Example: Protozoan Euplotes with endosymbiotic algae.
210
What is **commensalism**?
One partner benefits while the other receives neither benefit nor harm
## Footnote
Example: The 'satellite phenomenon' in cultured microbes.
211
What is an example of **commensal organisms**?
Microbes that occupy a niche on the human body and feed off dead skin and secretions
## Footnote
They do not usually cause harm.
212
What is **parasitism**?
A symbiotic relationship that is beneficial to the parasite and harmful to the host
## Footnote
Parasitism is widespread throughout nature, affecting all organisms.
213
True or false: Parasitism is primarily beneficial to the host.
FALSE
## Footnote
Parasitism is harmful to the host and beneficial to the parasite.
214
What is the most extreme form of **parasitism**?
Obligate intracellular parasitism
## Footnote
This form means the microbe spends all or most of its life cycle inside the host cell, deriving essential nutrients.
215
Name examples of **obligate intracellular parasites**.
* Viruses
* Rickettsia
* Chlamydia
* Apicomplexan protozoans like Plasmodium
## Footnote
These examples include genetic, metabolic, and energy parasites.
216
What types of harm can **parasites** cause to their hosts?
* Superficial damage (e.g., ringworm)
* Significant damage (e.g., peptic ulcers)
* Rapid death (e.g., rabies virus)
## Footnote
The extent of damage varies based on the type of parasite.
217
What is **syntrophy**?
Communal feeding between organisms sharing a habitat
## Footnote
Products given off by one organism are usable by another, benefiting both.
218
Give an example of a **syntrophic association**.
* Cellulomonas and Azotobacter
## Footnote
Cellulomonas digests cellulose into glucose, while Azotobacter fixes nitrogen gas and releases ammonium.
219
What does **amensalism** describe?
An action of one microbe causing an adverse effect in another
## Footnote
It usually involves antagonism or competition in a shared environment.
220
What is **antibiosis**?
The release of natural chemicals or antibiotics that inhibit or kill microbes
## Footnote
Many fungi and bacteria use this survival strategy.
221
How do certain ants protect their **fungal gardens**?
By cultivating actinomycetes that produce antibiotics
## Footnote
This protects the fungi from invasion by parasites.
222
What are **biofilms**?
Complex organized layers of microbes attached to a substrate
## Footnote
They result from an extracellular matrix that binds the organisms together.
223
True or false: Biofilms are uncommon and do not dominate the structure of most natural environments.
FALSE
## Footnote
Biofilms are among the most common and prolific associations of microbes.
224
What is the **adaptive strategy** of microbes forming biofilm communities?
An ancient and effective strategy that favors microbial persistence and offers greater access to life-sustaining conditions
## Footnote
Biofilms operate as 'superorganisms' influencing microbial activities like adaptation, nutrient cycling, and infections.
225
True or false: Individual cells in multicellular organisms have the capacity to produce, receive, and react to **chemical signals**.
TRUE
## Footnote
This capacity was historically attributed only to multicellular organisms, but it is now recognized in microbes as well.
226
What is **quorum sensing**?
A process involving self-monitoring of cell density, secretion of chemical signals, and genetic activation
## Footnote
It explains the development and behavior of biofilms.
227
Fill in the blank: Early in biofilm formation, free-floating microbes are often described as __________.
planktonic
## Footnote
These microbes are attracted to a surface and settle down to form biofilms.
228
What do cells secrete upon settling to form a biofilm?
A slimy or adhesive matrix, usually made of polysaccharide
## Footnote
This matrix binds the cells to the substrate.
229
What are **inducer molecules**?
Molecules released by attached cells that accumulate as the cell population grows
## Footnote
They help monitor population size and stimulate gene expression.
230
What is a **quorum** in the context of biofilms?
A critical number of cells that ensures sufficient quantities of inducer molecules
## Footnote
This accumulation allows the biofilm to react as a unit.
231
How do biofilms coordinate the expression of genes?
By simultaneously producing large quantities of proteins, such as enzymes or toxins
## Footnote
This regulation accounts for rapid breakdown of substrates and toxin release by pathogens.
232
What insight has quorum sensing provided regarding **pathogens**?
Understanding how pathogens invade hosts and produce damaging substances
## Footnote
It has been well studied in pathogenic bacteria like Pseudomonas aeruginosa.
233
Which bacteria commonly form biofilms on inanimate medical devices and in wounds?
Staphylococcus aureus
## Footnote
These biofilms can complicate infections and treatment.
234
What is the role of **Streptococcus species** in biofilms?
They are the initial colonists that create dental plaque on tooth surfaces
## Footnote
This highlights the importance of biofilms in oral health.
235
True or false: Most biofilms observed in nature are **monomicrobial**.
FALSE
## Footnote
Most biofilms are polymicrobial, involving multiple species.
236
What is a significant benefit of communication within a **biofilm**?
Sustaining overall partnerships among coexisting organisms
## Footnote
This communication supports specific niches and genetic transfers.
237
What types of genetic transfers occur among neighboring cells in biofilms?
* Conjugation
* Transformation
## Footnote
These processes contribute to genetic diversity and adaptation.
238
Define **growth** in the context of microbial nutrition.
Growth occurs when microbes become metabolically active and increase in size and number
## Footnote
Growth takes place on two levels: synthesis of new cell components and increase in population size.
239
What is the process of **binary fission**?
The division of a bacterial cell where one cell becomes two
## Footnote
It involves the parent cell enlarging, duplicating its chromosome, and forming a central transverse septum.
240
How is **population growth** measured in microbial cultures?
By counting the number of cells in the population
## Footnote
Population growth is significant in microbial control, infectious disease, and biotechnology.
241
What are the stages in the **population growth curve**?
* Lag phase
* Log phase
* Stationary phase
* Death phase
## Footnote
Each stage has practical importance in understanding microbial growth dynamics.
242
What techniques are used to **detect and count cells** in culture?
* Microscopy
* Viable cell counts
* Turbidity measurements
## Footnote
These techniques help in assessing microbial populations.
243
The time required for a complete fission cycle is called the **________**.
generation
## Footnote
This is also referred to as the doubling time.
244
What happens during **chromosome replication** in bacterial cell division?
* Parent cell duplicates its chromosome
* Chromosomes affix to the cytoskeleton
## Footnote
This is crucial for ensuring that each daughter cell receives a copy of the genetic material.
245
What is formed during the **septation** stage of binary fission?
A septum that begins to wall off the new cells
## Footnote
This process is essential for creating two separate daughter cells.
246
What occurs at the **completion of the cell division cycle**?
* Daughter cells become independent units
* Some species may remain attached, forming chains or pairs
## Footnote
This variability affects how different bacterial species grow and reproduce.
247
What is the process by which bacterial populations double with each new cell division or generation?
Binary fission
## Footnote
This process leads to exponential growth of the population.
248
The average **generation time** for bacteria under optimum conditions is approximately how long?
30 to 60 minutes
## Footnote
Some bacteria can have generation times as short as 5 to 10 minutes.
249
What is the generation time of **Mycobacterium leprae**, the cause of Hansen's disease?
10 to 30 days
## Footnote
This is one of the longest generation times among bacteria.
250
True or false: Most pathogens have relatively short doubling times.
TRUE
## Footnote
For example, Salmonella enteritidis and Staphylococcus aureus double in 20 to 30 minutes.
251
What is the formula used to calculate the total number of cells in a bacterial population during growth?
N_t = (N_i)2^n
## Footnote
N_t is the total number of cells, N_i is the starting number, and n is the generation number.
252
In the equation N_t = (N_i)2^n, what does the variable 'n' represent?
The generation number
## Footnote
It denotes how many times the population has doubled.
253
How many bacterial cells will be present in an egg salad sandwich after sitting in a warm car for 4 hours if the initial number of cells is 10 and the generation time is 20 minutes?
40,960 cells
## Footnote
Calculation: N_t = 10 x 2^12 = 40,960.
254
What type of graph is preferred for plotting bacterial growth due to easier readability of cell numbers?
Logarithmic graph
## Footnote
It provides a straight line indicative of exponential growth.
255
What does plotting the number of cells arithmetically produce?
A constantly curved slope
## Footnote
This contrasts with the straight line seen in logarithmic plots.
256
Fill in the blank: The term **generation** in bacteria refers to the period between an individual's birth and the time of producing _______.
offspring
## Footnote
This is similar to the meaning of generation in humans.
257
What is the mathematical representation of the cell population size in exponential growth?
2 raised to an exponent
## Footnote
Examples include 2^1, 2^2, 2^3, etc.
258
What is the **method traditionally used** to observe the population growth pattern in bacteria?
Viable count technique
## Footnote
This technique involves sampling live cells in a culture, growing them, and counting during a growth period.
259
What does one **colony on a plate** represent in microbiology?
One cell or colony-forming unit (CFU)
## Footnote
This principle is crucial for estimating the population size from a sample.
260
What are the **stages in the normal growth curve** of a bacterial population?
* Lag phase
* Exponential growth (log) phase
* Stationary phase
* Death phase
## Footnote
These phases occur in a closed system where nutrients and space are finite.
261
In the **viable plate count** method, what is used to quantify the population size?
A tiny measured sample of the culture
## Footnote
This sample is plated on solid medium to develop isolated colonies.
262
True or false: The **growth curve** is determined by graphing the number of colonies for each sample over the entire incubation period.
TRUE
## Footnote
This graphing helps visualize the growth trends of the bacterial population.
263
What can cause some samples to give a **zero reading** in the early stages of bacterial growth?
Scarcity of cells
## Footnote
Even if viable cells are present, the sampling may remove enough cells to alter tabulations.
264
What is the **total estimated cell population** in a flask based on?
Multiplication of the number of colonies by the container's volume
## Footnote
This provides a fair estimate of the total population size at any given point.
265
Fill in the blank: The **growth curve** typically produces a curve over a growth period of _______ days.
3 to 4
## Footnote
This duration is common for observing bacterial growth in a closed system.
266
What is the **initial step** in establishing a growing bacterial population in a flask?
Inoculating a flask with a known quantity of sterile liquid medium
## Footnote
This step is crucial for starting the batch culture method.
267
What are the **four phases** of bacterial growth in a culture?
* Lag phase
* Exponential growth phase
* Stationary phase
* Death phase
## Footnote
Each phase represents different growth dynamics and conditions affecting the bacterial population.
268
During the **lag phase**, why does the population appear not to be growing?
* Newly inoculated cells require adjustment
* Binary fission cycle not at maximum rate
* Sparse population may be missed in sampling
## Footnote
Individual cells remain metabolically active during this phase.
269
In the **exponential growth phase**, what conditions allow the population to grow geometrically?
* Adequate nutrients
* Favorable environment
## Footnote
Growth is balanced and genetically coordinated during this phase.
270
What happens during the **stationary phase** of bacterial growth?
* Population reaches size limit
* Some cells divide slowly or stop dividing
* Rate of death balances rate of multiplication
## Footnote
The number of viable cells remains relatively constant during this period.
271
What factors contribute to the decline in growth rate during the **stationary phase**?
* Depletion of nutrients and oxygen
* Accumulation of organic acids and toxic biochemicals
## Footnote
These factors lead to a balance between cell division and death.
272
What is the **death phase** characterized by?
* Decline in population size
* Some cells enter dormancy
* Some cells undergo programmed cell death
## Footnote
Persistent members may survive by utilizing nutrients from dead cells.
273
True or false: Microbes in the **exponential growth phase** are more vulnerable to antimicrobial agents than those in the stationary phase.
TRUE
## Footnote
Actively growing cells are more susceptible to conditions that disrupt metabolism and binary fission.
274
What implications does understanding the **growth curve** have in microbial control and infection?
* Stages of infection
* Spread of bacteria in early stages
* Faster multiplication can overwhelm host defenses
## Footnote
Knowledge of growth patterns is crucial for managing infections and microbial cultures.
275
Why is it unwise to incubate a culture beyond the **stationary phase**?
* Reduces number of active cells
* Culture could die out completely
## Footnote
It is preferable to conduct tests on young cultures for accurate results.
276
What is the **method** used for estimating the size of a microbial population through cloudiness?
Turbidometry
## Footnote
This technique observes that a clear nutrient solution becomes cloudy as microbes grow.
277
What instrument measures the ability of cells to scatter light in a liquid culture?
Spectrophotometer
## Footnote
It measures absorbance, indicating the amount of growth or cell mass in the culture.
278
In turbidometry, a **greater turbidity** indicates what?
A higher microbial count
## Footnote
Turbidity is a visual indicator of microbial growth in a culture.
279
What is the **direct cell count** method used for?
Counting the number of cells in a sample microscopically
## Footnote
This method uses a cytometer calibrated for small samples.
280
What is a limitation of the direct cell count and spectrophotometry methods?
They cannot distinguish between live and dead cells
## Footnote
Both methods include both types of cells in their counts.
281
What does the **Coulter counter** do?
Electronically scans a culture to detect and register cells
## Footnote
It counts cells as they pass through a tiny pipette.
282
What is the purpose of a **flow cytometer**?
Counting, sorting, sizing, and identifying cells in suspension
## Footnote
It uses fluorescent dyes and lasers to analyze cells.
283
True or false: The **chemostat** maintains a culture in a biochemically active state.
TRUE
## Footnote
It prevents the culture from entering the death phase by continuously supplying nutrients.
284
What are the **two techniques** mentioned for assaying microbial content in water?
* Most Probable Number (MPN)
* Membrane filtration
## Footnote
These techniques are discussed later in the book.
285
What is the **advantage** of using a chemostat in microbial growth?
It stabilizes the growth rate and cell number
## Footnote
This is crucial for maintaining consistent production in industrial applications.
Microbiology
flashcards
Decks in class (36)
# Cards
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Chemistry & Biochemistry49
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Ch 8 Metabolic109
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Ch. 13 Microbes131
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Ch, 4 Prokaryotes54
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Midterm Prep214
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Ch 189
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Ch. 2104
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Ch. 489
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Practice Test140
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Scientific Disease Names10
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Euk Vs Prok167
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DNA Rep27
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Lab Practicum19
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Ch. 5 Eukaryotes245
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Ch. 6147
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Ch. 9386
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Test 2 Review132
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#11-51 Cards31
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Ch. 7285
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Ch. 11349
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Ch. 12415
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Extra 12450
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Lab Review128
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Lec 3 Review64
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Ch 1456
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Disease Cards 21-28, 52-6825
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Disease Card Quiz177
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Ch. 15315
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Ch. 16319
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Final Study Guide174
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#10-20137
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#21-31169
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#32-43155
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#44-54160
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#55-68211
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Ch 1748
